Both the iPad Air and the Kindle Fire HDX comes with what is universally known as 'retina' displays, that is, a display where the pixels are so small that at normal viewing distances they cannot be made out.

• The iPad Air is equipped with a 9.7-inch 2048-by-1536 resolution display with a pixel density of 264 pixels per inch.
• The Kindle Fire HDX comes with a 8.9-inch 2560-by-1600 resolution display with a pixel density of 339 pixels per inch. The panel is also described as offering perfect color accuracy (100% sRGB).

See also: Gift Guide 2013: Awesome Kindle Fire HDX accessories  

Verdict

Technically, both displays fall into the 'retina' category, which means that at normal viewing distances the pixels will be too small for the human eye to make out. However, the higher pixel density of the Kindle Fire HDX means that you can hold the tablet closer to your face and still get a 'retina' experience.

So, if it's size you want, the iPad Air is for you, but if quality is what you are after, then you should opt for the Kindle Fire HDX. 

(Image source: Apple and Amazon)

At the heart of all tablets is a processor, and while the screen is what we look at, the processor can make or break a device.

• The iPad Air makes if of Apple's dual-core ARMv8-A 64-bit A7 processor running at 1.4GHz and a PowerVR G6430 GPU.
• The Kindle Fire HDX features 2.2GHz quad-core Snapdragon 800 processor, which also features an Adreno 330 GPU.

Verdict

This is a tough call. Apple's A7 is undoubtedly a fast processor , and can see to make a dual-core part that can outperform quad-core offerings, but the Snapdragon 800 has more cores to throw at heavy tasks when the going gets hard.

Since I'm convinced that in both cases the processing power is adequate, I'm calling this one a tie.

(Image source: Apple and Amazon)

Apps, photos, and videos all take up storage space on tablets, so you want enough to hold all of your digital life.

• Apple offers the iPad Air in 16BG, 32GB, 64GB, and 128GB versions, with each storage bump adding $100 to the price. There is no option for expanding storage by using microSD cards.
• Amazon offers the Kindle Fire HDX is 16GB, 32GB, and 64GB versions, with each storage bump adding $50 to the price. There is no option for expanding storage by using microSD cards.

Verdict

Unless you want 128GB of storage space – and most people don't – then the Kindle Fire HDX is the winner here because Amazon has priced the storage far more reasonably than Apple has.

(Image source: Apple and Amazon)

Size and weight are a concern when you expect to hold a device for extended periods.

• The iPad Air is svelte product, weighing in at just one pound, and measuring 9.4 inches by 6.6 inches by 0.29 inch (240 mm x 169.5 mm x 7.5 mm).
• The 8.9-inch Kindle Fire HDX measures 9.09 inches by 6.22 inches by 0.31 inches (231 mm x 158 mm x 7.8 mm) and is actually lighter than the iPad Air, weighing in at only 0.84 lbs.

Verdict

The Kindle Fire HDX is smaller and lighter than the iPad Air, which is to be expected given that it has a smaller screen, but if size and/or weight are a concern, then this is another win for Amazon. 

(Image source: Apple and Amazon)

Down to the dollars and cents.

• The iPad Air starts at $499 for the 16GB Wi-Fi-only model, while the 16GB Wi-Fi plus cellular version costs $629.
• The 7-inch Kindle Fire HDX starts at $229 for a 16GB Wi-Fi-only model, with the 16GB Wi-Fi plus cellular costs $329. The 8.9-inch Kindle Fire HDX starts at $379 for a 16GB Wi-Fi-only model, with the 16GB Wi-Fi plus cellular costs $479.

Verdict

If the choice is down to price, the Kindle Fire HDX is the clear winner. You can pick up an 8.9-inch Kindle Fire HDX with 64GB of storage and Wi-Fi plus LTE for less than the cost of a 16GB Wi-Fi plus cellular iPad Air. 

Another hands-down win for Amazon.

(Image source: Apple and Amazon)

Two totally different platforms.

• The iPad Air runs Apple's latest iOS 7 operating system, and apps are restricted to those available from the App Store.
• The Kindle Fire HDX runs a heavily modified version of Android 4.2.2, which Amazon calls Fire OS 3.0. Apps are restricted to Amazon's App Store and users cannot use Google's Play store.

See also: The very best tablets of 2013  

Verdict

To be honest, when it comes down to which app store is best, it is pretty much a matter of personal preference. Apple's App Store is probably the biggest and best curated, but there's nothing wrong with Amazon's offering either. I use both, and while on the whole I fnd that Apple has a better selection of apps, Amazon's it not bad either.

If you're already locked to one ecosystem or another then this might sway you, but otherwise it's not really much of an issue which you happen to choose.

(Image source: Apple and Amazon)

Wanna take selfies? Want to ditch the dSLR at home but still be able to grab cool shots?

• The iPad Air has a 5-megapixel/1080p rear-facing camera which features a five-element lens and F2.4 aperture, giving it excellent low-light capability. It also features a 1.2-megapixel/720p front-facing camera.
• Both the 7-inch and 8.9-inch Kindle Fire HDX tablets have a 1.2-megapixel/720p front-facing camera, while the 8.9-inch tablet also comes with an 8-megapixel rear-facing camera.

Verdict

Not much to separate the two here.

(Image source: Apple and Amazon)

How long can you do things on your tablet before needing to hook up to a power supply?

• For the iPad Air, Apple promises up to 10 hours of surfing the web on Wi-Fi, watching video, or listening to music.
• Kindle Fire HDX get 12 hours of reading, surfing the web on Wi-Fi, watching video, or listening to music on the 8.9-inch version, with this dropping down an hour for the 7-inch version.

Verdict

Despite the iPad Air offering excellent battery life compared to many tablets on the market, Amazon manages to win again.

(Image source: Apple and Amazon)

Want to glam up your tablet?

• Apple has the broadest accessory ecosystem, with no end of accessories that you can connect or wrap of use with your iPad Air, from cases to model aircraft.
• You can get a decent selection of cases for the Kindle Fire HDX, but apart from that, that's about it.

Verdict

If you're looking for a mature ecosystem of accessories to go with your tablet then the iPad Air is the one to go for here.

(Image source: Apple and Amazon)

So, which is the best tablet of the two?

See also: Gift Guide 2013: Awesome Kindle Fire HDX accessories  

Personally, I think the Kindle Fire HDX is the better of the two. It's cheaper, lighter, has a better screen, and storage costs are more reasonable if you want something beyond the base 16GB.

The iPad Air is a great tablet, but the Kindle Fire HDX is better.

However, if you want to be with the cool kids then you may still want to go with the iPad Air. It's without a doubt the flagship tablet, instantly recognizable and gives owners access to a huge ecosystem of apps and accessories. If you already own an iPhone or an older iPad, and have made an investment in apps, this may sway you.

Bottom line, both are awesome tablets and you won't be disappointed with either of them.

(Image source: Amazon)